Conventionally, a cartridge method has been used in an image forming apparatus that performs an electrophotographic image forming process. In the cartridge method, an image bearing member and a process means that acts on the image bearing member are integrated into a cartridge, which can be attached to and removed from the image forming apparatus. The cartridge method is very user friendly in that users can perform maintenance on the apparatus without relying on service persons. The cartridge method has been widely used in image forming apparatuses.
Conventionally, a process cartridge has included a developing device that develops an electrostatic latent image on an image bearing member with developer. The developing device includes a developing chamber internally provided with a developer bearing member, and a developer containing chamber configured to contain developer. The developing chamber and the developer containing chamber have an opening (developing opening) therebetween, which allows developer to pass therethrough. An agitating means supplies developer from the developer containing chamber to the developing chamber.
The agitating means includes a shaft member rotatably provided in the developer containing chamber, and an elastic sheet secured to the shaft member. A configuration is known in which, in order for the agitating means to smoothly supply developer to the developing chamber and loosen dense developer in the developing chamber, a leading edge of the elastic sheet enters the developing chamber from the developer containing chamber (see Patent Literature (PTL) 1).
Since the developing device has the developing opening which serves as a path of the developer, the strength of the developing device may be degraded. For adding strength to the developing device, two opposite sides of the developing opening extending in the axial direction of the developer bearing member may be partially connected to each other by a connecting part, such as a rib.
However, the connecting part hinders the leading edge of the elastic sheet from entering the developing chamber. To solve this problem, the elastic sheet may have a notched portion at a position facing the connecting part so as to avoid contact with the connecting part (see PTL 2). With this configuration, however, the developer around the connecting part may not be able to be conveyed to the developing chamber, or the developer on the back side of the connecting part may not be able to be loosened.
There is a configuration in which the developing chamber also includes an agitating means. This configuration, which requires a total of two agitating means, may cause an increase in cost and size of the apparatus (see PTL 3).